In the prior art, as for a permanent magnet adjustable-speed motor, the terminal components of the motor, which is made of common steel, is apt to generate heat due to the influence of electric eddy currents. Based on the law of electromagnetic induction, the induced electromotive force E=dψ/dt. The greater the frequency and the less dt are, the greater the induced electromotive force E is. Accordingly, the induced current increases and the generated heat increases, and the temperature is so high that the reliability turns bad even to cause potential safety hazard. Especially for a centrifugal refrigeration compressor which utilizes a permanent magnet adjustable-speed motor, if the terminal board generates much heat, a sealing failure may be caused, resulting in leakage of the coolant for cooling the motor.
While the terminal component of the motor, which is made of electrical insulating materials, has a large volume, is difficult to produce, and has low reliability.
In view of the defects above, the inventors finally obtained the present invention after a long period of research and practice.